From DE-GM 94 00 445.5, a lighting device is known with an optical system consisting of a lamp, a reflector arranged on one side of the lamp, and a condenser arranged on the other side of the lamp. A support is provided for a light pipe aligning the lamp's input end with the condenser. In practice, there is often a need for carrying out simultaneous irradiations with two light pipes in order to avoid shadows or to apply a greater light intensity to an object. This is required, for example, in order to shorten the hardening time of UV-hardened adhesives in an industrial adhesive-bonding process.
When fiber-optic light pipes are used, the fiber bundle can be split, after the light-input end where all fibers are still joined, into two or more partial bundles. A corresponding fraction of the entire irradiated light energy may be transmitted via such bundles. In the case of liquid light-pipes, however, such splitting cannot be carried out in the same manner. Instead, two separate correspondingly thinner hoses must be coupled to one common light connection, in which connection these hoses are also separately terminated. The two round hose cross-sections, however, can only each have one-half the diameter of the undivided light pipes so that part of the light output supplied by the condenser does not reach the light pipe. Consequently, with the present state of the art, the coupling of several liquid light-pipes to a single light source does not allow the full utilization of the amount of light produced by the lamp in the condenser's focal spot. Therefore, whenever a greater output of light was needed, individually separate lamps and/or light sources had to be used.